"You have been logged on with a temporary profile" – Windows 7, keep working!

Today, I started my computer and logged in. I entered my password, hit “Enter” and was shocked about the message “Preparing Desktop” which normally only appears when logging in the first time on a fresh installed system.

After a while, I saw a plain desktop (default background image and all customizations lost). Then a popup showed up – see image on the right. This popup told me (it seems that they did not translate it yet – I have a German version of Windows 7 RC):